ZackH Posted November 22, 2011 Share Posted November 22, 2011 Speaking of models, 00z NAM is out... And not to stoke the fire or anything, but here's a snippet out of BMX's PIS for tomorrow: I saw this. It will be interesting to see what the next few model runs do and to get a look at what the Hi-Res models are doing come the morning. All the Hi-Res stuff so far seems to agree with the linear mode but most do not have runs that are into the best dynamics for tomorrow yet. This is just a sensitive area of the country after April 27th and there is another board out there with folks freaking out and thinking this will be another April 27th and I can't stand that. You tweak a few things here and there and tomorrow could be substantial, but the models have been slowly progressing towards a less serious solution with very little jumping around. When you see that, there is rarely a whole lot of drastic change in the last 24 hours leading up to an event. Link to comment Share on other sites More sharing options...
ZackH Posted November 22, 2011 Share Posted November 22, 2011 Btw: I've been watching the discussion on talk wx and am not exactly impressed with the way you are going about things there, js. You are free to PM me about that, but it is completely out of line for you to do this in a thread. Link to comment Share on other sites More sharing options...
andyhb Posted November 22, 2011 Author Share Posted November 22, 2011 Fair enough, but keep that in mind in the future... Link to comment Share on other sites More sharing options...
andyhb Posted November 22, 2011 Author Share Posted November 22, 2011 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1159 PM CST MON NOV 21 2011 VALID 221200Z - 231200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GULF COASTAL STATES NEWD INTO THE TN AND LOWER OH VALLEYS... ...SYNOPSIS... UPPER LEVEL TROUGH...CURRENTLY LOCATED IN THE SRN PLAINS...IS FORECAST TO SHIFT RAPIDLY ENEWD THROUGH THIS PERIOD...WITH THE TROUGH AXIS EXPECTED TO BE SITUATED FROM ERN OH SWD INTO GA BY EARLY WED MORNING. AHEAD OF THIS TROUGH...A SURFACE LOW WILL DEEPEN AS IT MOVES FROM SERN MO NEWD INTO ERN PA...WITH A COLD FRONT TRAILING SWWD FROM THE LOW. ...SERN TX/LOWER MS VALLEY... A LINE OF STORMS HAVE DEVELOPED WEST OF THE FRONT ACROSS CENTRAL TX. THESE STORMS WILL CONTINUE TO SHIFT EWD OVERNIGHT AND SHOULD BECOME ALIGNED WITH THE FRONT. THEREAFTER...THE STORMS SHOULD ACCOMPANY THE FRONT THROUGH SERN TX/LA LA DURING THE MORNING HOURS. WIND FIELDS WILL BE SUPPORTIVE OF SEVERE STORMS...EVEN MID LEVEL ROTATION...THOUGH WEAK MID LEVEL LAPSE RATES MAY INHIBIT UPDRAFT STRENGTH. IN ANY CASE...THE LINEAR NATURE OF THE STORMS COMBINED WITH THE RICH BOUNDARY LAYER MOISTURE AND STRONG WIND FIELDS SUGGESTS WIND DAMAGE WILL BE POSSIBLE UNTIL THE STORMS PASS THROUGH THE AREA DURING THE MORNING. ...CENTRAL GULF STATES NWD INTO THE TN AND LOWER OH VALLEYS... THE BEST FORCING AND STRONGEST WIND FIELDS WILL GENERALLY BE LOCATED FROM TN NWD...WHILE THE STRONGEST INSTABILITY...MLCAPES TO 1000 J/KG ARE EXPECTED TO BE SOUTH OF TN. WHILE THIS COMBINATION IS NOT IDEAL FOR A MORE ROBUST SEVERE OUTBREAK...THE INSTABILITY AND SHEAR SUPPORT A THREAT FOR SEVERE WEATHER ACROSS A LARGE AREA AHEAD OF THE APPROACHING UPPER TROUGH/FRONT. STRONG LINEAR FORCING FAVORS A LINE OF STORMS EITHER INTENSIFYING OR REDEVELOPING ALONG THE FRONT BY MIDDAY. THE FAST PACE OF THE UPPER SYSTEM SUPPORT THIS LINEAR SYSTEM MOVING EWD AT 35-40 KT. THE LINEAR SYSTEM PLUS STRONG ENVIRONMENTAL WIND PROFILES INDICATE WIND DAMAGE SHOULD BE THE MAIN THREAT...WITH EMBEDDED BOWS/LEWPS. THE GREATEST WIND THREAT IS EXPECTED ACROSS PORTION OF TN/MS AND AL...WHERE THE GREATEST INSTABILITY AND STRONGER FORCING OVERLAP DURING THE AFTERNOON HOURS. THE LINEAR STORMS ARE EXPECTED TO SPREAD EWD INTO GA/WRN SC DURING THE EVENING...THOUGH THE WIND THREAT SHOULD GRADUALLY DIMINISH WITH WEAKENING INSTABILITY. THE STRONG LOW LEVEL SHEAR AND MOIST BOUNDARY LAYER SUGGESTS A COUPLE OF TORNADOES APPEAR MOST LIKELY IN THE TN/AL/MS PORTION OF THE SLIGHT RISK. WHILE WIND PROFILES ALSO APPEAR FAVORABLE FOR TORNADOES ACROSS KY...AS THE SURFACE LOW MOVES ACROSS THE STATE...THE VERY MOIST VERTICAL SOUNDINGS AND MUCAPES AOB 200 J/KG SUGGEST THE TORNADO THREAT IS LOW. ...NC... SQUALL LINE IS EXPECTED TO BE MOVING INTO AT LEAST NC BY 12Z WED MORNING. WIND FIELDS AND VERTICAL SHEAR WILL BE QUITE STRONG AND SUPPORTIVE OF AN ISOLATED WIND OR TORNADO THREAT. HOWEVER...VERY MOIST VERTICAL SOUNDINGS AND MARGINAL INSTABILITY PRECLUDE A SLIGHT RISK ISSUANCE ATTM. ..IMY/LEITMAN.. 11/22/2011 Link to comment Share on other sites More sharing options...
brettjrob Posted November 22, 2011 Share Posted November 22, 2011 After perusing the guidance this evening, my impression is also that this is unlikely to live up to some of the chatter of recent days. We'll see what the morning brings, and whether any additional instability and/or low-level backing can be realized across the Mid South. Link to comment Share on other sites More sharing options...
tornadotony Posted November 22, 2011 Share Posted November 22, 2011 After perusing the guidance this evening, my impression is also that this is unlikely to live up to some of the chatter of recent days. We'll see what the morning brings, and whether any additional instability and/or low-level backing can be realized across the Mid South. I cannot settle on a preferred view of this event. I really can't. On one hand, guidance has been trending toward a less impressive result overall, yes. But I'm starting to wonder about a few things. 1) The RUC and the 06z NAM keep winds incredibly backed in the warm sector at least through 18z...the NAM even to 21z...and by this I mean NOWHERE ahead of the cold front veers to greater than 180°. This is a rather substantial difference from the 00z guidance and I feel warrants intense scrutiny. If that indeed turns out, you at least increase the threat for tornadoes associated with the squall line/QLCS...if we get one...which leads me to... 2) I am not 100% positive that a squall line forms along the cold front tomorrow. For this, I've made a list of pros and cons, pro favoring a QLCS/squall line: PROS: -Veering-backing winds with height. -Weak CINH along front. CONS: -Shear vectors likely to be at least 60° from parallel along the front. Usually, you would want to see them more parallel. -Though CVA/large scale lift is present and supportive of thunderstorms, I'm not sure it's overwhelming enough to compensate for the first con. Which one wins? I'm not sure. The 00z EMC WRF seems to indicate that a solid line never really forms along the front tomorrow and instead leaves activity discrete. I'm not 100% sure I buy that yet. 3) The last several runs of the NAM have been persistent with bringing out a weak vort max ahead of the front tomorrow afternoon across MS/AL. Would this be enough to trigger prefrontal storms? If so, what character would they have? That question leads me to my next few points. 4) When it comes to forecasting tornado potential (not looking so much at strong tornadoes as tornadoes overall), I think it's important to look even more at directional shear than speed shear. If (BIG IF) point #1 pans out, we may still lack a bit in low-level speed shear (though the 06z NAM does have 35-40kt winds at 850mb at 21z in MS/AL), but directional shear would most certainly NOT be lacking (again big IF to #1 actually panning out). 5) I really discourage turning a back to a late November setup with (rather) steep lapse rates (they're even halfway decent in the precip-loaded forecast soundings along the front) and incredible low-level moisture. Those are the two things that most often haunt our cold-season events. If I'm looking for severe weather this time of year, I'd rather have worries about shear over worries about instability and moisture, because if you have the latter, occasionally the former will work itself out. 6) I believe there is an overlooked wildcard in this setup: the Carolinas. Along the lee of the Apps, you get a natural temp gradient at the surface due to the changes in elevation. As large-scale ascent overtakes the area, you can get mesolows to form along this natural gradient. Given that the Carolinas will have plenty of moisture, decent lapse rates, a strengthening nocturnal low-level wind max, and this temp gradient, I wouldn't be shocked if the Carolinas are being sorely overlooked in terms of their potential tomorrow night. This is supported by the 00z EMC WRF, which has intensification of convection tomorrow night in nrn GA and the Piedmont. Overall, I'm about as unsure about tomorrow's outcome as I've felt about any severe event in a long time. I could see it going multiple ways. One would be that the system is simply not strong enough to keep flow backed enough at the sfc, and thus the winds veer out, and with there not being a ton of linear forcing, we don't even see a decent squall line tomorrow. That's one extreme. The other extreme is that we once again have to play catchup w/r/t LL shear tomorrow, and we see a few tornadic supercells in MS/AL, with potentially another max in the event in the Piedmont of the Carolinas. That would be the max that I could forsee. To be honest, I don't know where tomorrow lies. I don't think anyone will know until just before we get rolling. I hope this makes sense and isn't too convoluted. Link to comment Share on other sites More sharing options...
andyhb Posted November 22, 2011 Author Share Posted November 22, 2011 I hope this makes sense and isn't too convoluted. Excellent way to sort out things here, easy to read and good analysis as a whole. Link to comment Share on other sites More sharing options...
Jim Martin Posted November 22, 2011 Share Posted November 22, 2011 Looking like more of a linear event for Mississippi & Alabama later today. Link to comment Share on other sites More sharing options...
tornadotony Posted November 22, 2011 Share Posted November 22, 2011 Not a fan of what I see developing near and S and SE of Meridian...that needs to be watched... Link to comment Share on other sites More sharing options...
jrips27 Posted November 22, 2011 Share Posted November 22, 2011 Not a fan of what I see developing near and S and SE of Meridian...that needs to be watched... I just saw those. Wouldn't be surprised to see a few watches go up over the next 1-2 hours. Also a nasty bow echo went through just to the south of Jackson, MS. Link to comment Share on other sites More sharing options...
CandymanColumbusGA Posted November 22, 2011 Share Posted November 22, 2011 I just saw those. Wouldn't be surprised to see a few watches go up over the next 1-2 hours. Also a nasty bow echo went through just to the south of Jackson, MS. Watch likely to go out soon for portions of Alabama and Mississippi... The storms firing up north of Mobile certainly need to be watched over the next hour or so... They are INCREDIBLY warm out that way and getting more unstable by the minute. It's going to be an interesting day for them.... EDIT: It's now a Tornado WATCH until 5 PM local time... Some of the storms are really starting to blossom in that 1000 J/kg MLCAPE.... Link to comment Share on other sites More sharing options...
jrips27 Posted November 22, 2011 Share Posted November 22, 2011 There is the watch... DISCUSSION...A LINE OF THUNDERSTORMS OVER CENTRAL MS HAS INTENSIFIED AND ACCELERATED DURING THE PAST HOUR...AND WILL TRACK ACROSS THE WATCH AREA DURING THE NEXT FEW HOURS. STRONG WINDS ALOFT AND MESOSCALE ORGANIZATION OF LINE WILL POSE A THREAT OF DAMAGING WINDS. ALSO...ISOLATED DISCRETE CELLS FORMING AHEAD OF THE LINE MAY BECOME SUPERCELLULAR WITH A RISK OF DAMAGING WINDS OR ISOLATED TORNADOES. Hazar Link to comment Share on other sites More sharing options...
Brick Tamland Posted November 22, 2011 Share Posted November 22, 2011 Local TV mets around here are making it seem like it won't be that bad around here tonight, which makes me worry because it's supposed to come in overnight when people are sleeping. These things can blow up once they get here. Link to comment Share on other sites More sharing options...
tornadotony Posted November 22, 2011 Share Posted November 22, 2011 Looks like the cells in Choctaw, Marengo, and Hale Counties in AL might be gaining supercell characteristics. Link to comment Share on other sites More sharing options...
Isopycnic Posted November 22, 2011 Share Posted November 22, 2011 Local TV mets around here are making it seem like it won't be that bad around here tonight, which makes me worry because it's supposed to come in overnight when people are sleeping. These things can blow up once they get here. Where are you getting this data from? Link to comment Share on other sites More sharing options...
Gastonwxman Posted November 22, 2011 Share Posted November 22, 2011 SPC's thinking the severe threat isn't as great as was originally thought: DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0200 PM CST TUE NOV 22 2011 VALID 222000Z - 231200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE SERN STATES... ...SERN STATES... SEVERE PROBABILITIES HAVE BEEN LOWERED FROM MUCH OF THE TN VALLEY INTO ERN KY DUE TO LIMITED BUOYANCY. OTHERWISE...PRE-FRONTAL LINE OF STORMS CONTINUES FROM SERN TN SWWD THROUGH N-CNTRL AL TO THE MS-AL BORDER TO SRN LA. STRONGEST STORMS ARE MOVING INTO EXTREME WRN AL. OTHER MORE DISCRETE ACTIVITY IS DEVELOPING IN WARM SECTOR OVER CNTRL AND SRN AL WHERE INFLUX OF HIGHER THETA-E AIR EXISTS AND THE WEAKLY CAPPED BOUNDARY LAYER HAS BECOME MORE UNSTABLE. MLCAPE REMAINS MARGINAL DUE TO WEAK MID LEVEL LAPSE RATES...BUT THE BEST SHEAR/INSTABILITY PARAMETER SPACE RESIDES ACROSS CNTRL AND S-CNTRL AL AS OF LATE THIS AFTERNOON WITH 0-2 KM STORM RELATIVE HELICITY ON THE ORDER OF 150-250 M2/S2. STORMS IN THIS REGION WILL REMAIN CAPABLE OF PRODUCING ISOLATED DAMAGING WIND AND PERHAPS ISOLATED TORNADOES. SEVERE THREAT WILL DEVELOP EWD THROUGH GA AND THE CAROLINAS THIS EVENING AND TONIGHT IN ASSOCIATION WITH THE MIGRATORY UPPER TROUGH AND ITS ATTENDANT LLJ. THE KINEMATIC ENVIRONMENT WILL REMAIN FAVORABLE FOR ORGANIZED SEVERE STORMS WITH STRONG DEEP LAYER SHEAR AND LARGE HODOGRAPHS. HOWEVER...PRIMARY LIMITING FACTOR WILL CONTINUE TO BE WEAK INSTABILITY AND AN OVERALL MARGINAL THERMODYNAMIC ENVIRONMENT. FOR THIS REASON...CONFIDENCE IN A MORE WIDESPREAD SEVERE EVENT DECREASES WITH EWD EXTENT INTO THE CAROLINAS...BUT AREA WILL CONTINUE TO BE MONITORED. Link to comment Share on other sites More sharing options...
jrips27 Posted November 22, 2011 Share Posted November 22, 2011 New SPC update puts me in the 5% Tornado probs. It's muggy over here with a temp of 74oF and a dew of 61oF. Sun is still intermittently popping through. Link to comment Share on other sites More sharing options...
nrgjeff Posted November 22, 2011 Share Posted November 22, 2011 Looks like Tennessee and North Carolina can rest easy. Like the MD fading Tenn. Alabama stuff trying, but I'd start looking fwd to a national championship for excitement. Weather prolly won't deliver today, which is just as well for rattled nerves. Straight winds are possible but just not quite enough for torn. A differential heating boundary is setting up E/W approximately along I-20 from BHM to ATL; however, wind fields are sloppy. Okolona, Miss profiler (closest I can get) still shows veer, back, veer. The lower 3,000 FT is hosed from previous convection, but you can extrapolate. Remember most recent is left on these. However the right, approximate pre-storm environment in AL, also shows the slight but unfavorable veer, back, veer. Finally the main trough is positively tilted, lumbering, and starting to shear out on its way from Texas. All in all I think the Mets fading this are right on. It is a nice change from hype journalism. Happy I got my secondary WF idea right, but also happy for the good people of Alabama that storms are so linear. Link to comment Share on other sites More sharing options...
HWY316wx Posted November 22, 2011 Share Posted November 22, 2011 Where are you getting this data from? It's called BCI. Brick Central Intel Link to comment Share on other sites More sharing options...
LithiaWx Posted November 22, 2011 Share Posted November 22, 2011 The Atlanta Metro is in for some good rains. Perhaps I can crack the 1" mark for the storm total! Link to comment Share on other sites More sharing options...
SouthernNJ Posted November 22, 2011 Share Posted November 22, 2011 Storm just Northeast of Montgomery AL has some strong winds with it now. Link to comment Share on other sites More sharing options...
jrips27 Posted November 22, 2011 Share Posted November 22, 2011 THE THREAT FOR SVR TSTMS MAY INCREASE DURING THE NEXT FEW HRS ACROSS PORTIONS OF E-CNTRL/SERN AL...CNTRL GA...AND WRN SC. TRENDS WILL CONTINUE TO MONITORED FOR THE POSSIBLE ISSUANCE OF A WW EAST/NORTHEAST OF TORNADO WATCH 895. RECENT VISIBLE SATELLITE TRENDS SUGGEST BOUNDARY LAYER DESTABILIZATION IS UNDERWAY WELL IN ADVANCE OF A SYNOPTIC COLD FRONT CURRENTLY ALONG THE MS RIVER. NNE-SSW-ORIENTED BANDS OF LOOSELY-ORGANIZED...WAA-INDUCED CONVECTION ARE STREAMING NEWD OVER PORTIONS OF ERN AL AHEAD OF A LEADING-LINE/TRAILING-STRATIFORM MCS THAT RECENTLY PUSHED EAST OF THE AL/MS BORDER...WHICH WAS RESPONSIBLE FOR DMGG WIND GUSTS ACROSS PORTIONS OF E-CNTRL MS BUT IS CURRENTLY LOSING SOME ORGANIZATION. E OF THIS MCS...MLCAPE VALUES HAVE CLIMBED TO 500-1000 J/KG S OF I-20...WITH LOWER VALUES FARTHER NORTH. AND...WITH THE APPROACH OF A MID-LEVEL SHORTWAVE TROUGH...DEEP-LAYER ASCENT IS FORECAST TO INCREASE DURING THE NEXT FEW HRS...AND SFC PRESSURE FALLS AOA 2 MB PER 2 HRS HAVE ALREADY BEEN NOTED NORTH OF I-20. AS THE ASCENT IS AUGMENTED BY EFFECTIVE BULK SHEAR MAGNITUDES INCREASING TO 35-45 KT...ONGOING CONVECTION ACROSS AL MAY DEEPEN/ORGANIZE DURING THE NEXT FEW HRS AS IT APPROACHES GA/SC. DMGG WIND GUSTS WILL BE THE PRIMARY THREAT WITH QLCS AND LEWP STRUCTURES. HOWEVER...WITH LOW-LEVEL HODOGRAPHS FORECAST TO ENLARGE UPON INTENSIFICATION OF THE 925-850-MB FLOW /EFFECTIVE SRH VALUES REACHING 150-300 M2/S2 BY AROUND 00Z/...THE TORNADO THREAT WILL BE NON-ZERO. CONVECTIVE TRENDS WILL BE MONITORED FOR THE POTENTIAL ISSUANCE OF A WW...WITH A GREATER CHANCE FOR ISSUANCE AFTER 23Z. Link to comment Share on other sites More sharing options...
SouthernNJ Posted November 22, 2011 Share Posted November 22, 2011 Wonder if the storm north of Auburn will get its act together or not. It's had a mesocyclone for over an hour now. Link to comment Share on other sites More sharing options...
jrips27 Posted November 22, 2011 Share Posted November 22, 2011 HE NATIONAL WEATHER SERVICE IN PEACHTREE CITY HAS ISSUED A * TORNADO WARNING FOR... SOUTHEASTERN HEARD COUNTY IN WEST CENTRAL GEORGIA NORTHERN TROUP COUNTY IN WEST CENTRAL GEORGIA * UNTIL 645 PM EST * AT 604 PM EST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 12 MILES WEST OF LAGRANGE...MOVING NORTHEAST AT 30 MPH. * OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO HOGANSVILLE AND CORINTH. Link to comment Share on other sites More sharing options...
Snowless in Carrollton Posted November 22, 2011 Share Posted November 22, 2011 Pretty nasty little storm about to move through my area. Looks like it's bowing a little bit. Interesting that they just issued a tornado watch but one of the counties under a Tornado Warning ( Heard) isn't under a watch. I wonder why that is ? Link to comment Share on other sites More sharing options...
Gastonwxman Posted November 22, 2011 Share Posted November 22, 2011 New watch issued: URGENT - IMMEDIATE BROADCAST REQUESTED TORNADO WATCH NUMBER 896 NWS STORM PREDICTION CENTER NORMAN OK 615 PM EST TUE NOV 22 2011 THE NWS STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR PORTIONS OF CENTRAL GEORGIA EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 615 PM UNTIL 200 AM EST. TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. DISCUSSION...PRE-FRONTAL BAND OF TSTMS CONTINUE TO THRIVE ACROSS ECNTRL/SRN AL AND WILL MOVE ENE INTO CNTRL GA THROUGH THE EVE. PRESENCE OF SUFFICIENT LLVL/DEEP LAYER SHEAR WILL ENCOURAGE EMBEDDED ROTATING STRUCTURES WITH BRIEF TORNADOES. OTHERWISE...LEWPS/BOWS WILL GIVE LOCAL DMGG WIND GUSTS AND SMALL HAIL. Link to comment Share on other sites More sharing options...
AcworthWx Posted November 23, 2011 Share Posted November 23, 2011 Pretty steady showers and the first rumble&flash of the evening. Thankfully this line is shifting East or it could have gotten interesting here IMBY. Just saw that watch as well. Everybody south of KATL, stay safe down there. Link to comment Share on other sites More sharing options...
Brick Tamland Posted November 23, 2011 Share Posted November 23, 2011 Where are you getting this data from? History. Link to comment Share on other sites More sharing options...
Isopycnic Posted November 23, 2011 Share Posted November 23, 2011 History. you mean your arse? Link to comment Share on other sites More sharing options...
Brick Tamland Posted November 23, 2011 Share Posted November 23, 2011 you mean your arse? Maybe. But you do a good job acting like the other part in front. Link to comment Share on other sites More sharing options...
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